Nihil obstat (Latin for "nothing hinders" or "nothing stands in the way")[1][2] is a declaration of no objection to an initiative or an appointment.

Apart from this general sense, the phrase is used more particularly to mean an "attestation by a church censor that a book contains nothing damaging to faith or morals".[1] The Censor Librorum delegated by a bishop of the Catholic Church reviews the text in question, but the nihil obstat is not a certification that those granting it agree with the contents, opinions or statements expressed in the work; instead, it merely confirms "that it contains nothing contrary to faith or morals."[1]

The nihil obstat is the first step in having a book published under Church auspices. If the author is a member of a religious institute and if the book is on questions of religion or morals, the book must also obtain the imprimi potest ("it can be printed") of the major superior.[3] The final approval is given through the imprimatur ("let it be printed") of the author's bishop or of the bishop of the place of publication.[4]